The present disclosure relates to a three-dimensional image display device, and more particularly, to a three-dimensional image display device capable of alleviating unnaturalness and discomfort caused by a so-called reverse view.
Various three-dimensional image display devices are known which realize a stereoscopic view for an image observer observing two images having parallax. The system of the stereoscopic image display devices is largely divided into a glass system in which a parallax image is divided and input to the left and right eyes by using glasses and an unaided eye system in which a parallax image is input to the left and right eyes without using glasses.
As the three-dimensional image display devices of the unaided eye system, three-dimensional image display devices, that is, “autostereoscopic image display devices”, each acquired by combining an optical splitting unit that is formed by a parallax barrier or a lens sheet including a lens array, and an image display unit (two-dimensional image display device) haven been started to be practically used.
For example, an autostereoscopic image display device that uses a parallax barrier as the optical splitting unit is configured by an image display unit that is formed by a display panel including a plurality of pixels arranged in a two-dimensional matrix pattern in the horizontal direction and the vertical direction or the like and a parallax barrier including openings extending substantially in the vertical direction.
The autostereoscopic image display devices each including the optical splitting unit is largely divided into a type in which an optical splitting unit is arranged between an image display unit and an image observer, for example, as illustrated in FIG. 7 of JP-A-5-122733 and a type in which an image display unit includes an image display section such as a transmission-type liquid crystal display panel and an illumination section, and an optical splitting unit is arranged between the image display section and the illumination section, for example, as illustrated in FIG. 10 of Japanese Patent No. 3565391.
Conceptual diagrams of autostereoscopic image display devices in which the optical splitting unit is arranged between the image display section and the illumination section are illustrated in FIGS. 48A and 48B. The optical splitting unit is formed by a parallax barrier in the autostereoscopic image display device illustrated in FIG. 48A, and the optical splitting unit is formed by a lens sheet (lenticular lens) that includes a convex columnar lens array in the autostereoscopic image display device illustrated in FIG. 48B. In addition, the conceptual diagrams of autostereoscopic image display devices in which the optical splitting unit is arranged between the image display unit and an image observer are illustrated in FIGS. 49A and 49B. The optical splitting unit is formed by a parallax barrier in the autostereoscopic image display device illustrated in FIG. 49A, and the optical splitting unit is formed by a lenticular lens in the autostereoscopic image display device illustrated in FIG. 49B.
As illustrated in FIG. 48A, a group of rays of light emitted from pixel groups to which reference numerals L2, L4, L6, L8, and L10 are assigned reaches a viewpoint 1, and a group of rays of light emitted from pixel groups to which reference numerals R1, R3, R5, R7, and R9 are assigned reaches a viewpoint 2. As above, at a position located at a predetermined distance from the image display unit, an image of the viewpoint 1 and an image of the viewpoint 2 are alternately observed. This similarly applies to FIGS. 48B, 49A and 49B.
Here, it is assumed that the left eye and the right eye of the image observer are located at the viewpoint 1 and the viewpoint 2. When a left-eye image is displayed by the pixel groups to which the reference numerals L2, L4, L6, L8, and L10 are assigned, and a right-eye image is displayed by the pixel groups to which the reference numerals R1, R3, R5, R7, R9 are assigned, the image observer recognizes the images as a stereoscopic image. In other words, when located within an area in which the image of the viewpoint 1 is received in the left eye, and the image of the viewpoint 2 is received in the right eye, the image observer recognizes the images as a stereoscopic image.
However, when the image observer moves so as to be located within the area in which the image of the viewpoint 2 is received in the left eye, and the image of the viewpoint 1 is received in the right eye, a state called a “reverse view” in which the image of the left eye and the image of the right eye are viewed so as to be interchanged is formed. The image observer recognizes an image in which the front side and the inner side are reversed, whereby unnaturalness and discomfort are caused.
As attempts to alleviate unnaturalness and discomfort that are caused by a reverse view, for example, in JP-A-2000-47139, an autostereoscopic image display device in which the location of an image observer is detected, and the pattern shape of a mask pattern of an optical modulator corresponding to the optical splitting unit is changed or an autostereoscopic image display device in which the location of an image observer is detected, and the content of an image displayed on an image display unit is changed is proposed.